/**
 * Live ops wall — pure helpers (design-canvas/live-ops-wall-mockup.html,
 * gods-eye-view-notes.md top 5). No React here, so the logic is testable in
 * isolation and shared by MapView and LiveView.
 */
import type { AircraftTrack, CallRecord, Camera, IncidentRecord, Ny511Event, VesselTrack } from "@/lib/types";
import { severityRank } from "@/lib/severity";

export type LatLon = [number, number];

export function km(a: LatLon, b: LatLon): number {
  const R = 6371;
  const dLa = ((b[0] - a[0]) * Math.PI) / 180;
  const dLo = ((b[1] - a[1]) * Math.PI) / 180;
  const x =
    Math.sin(dLa / 2) ** 2 +
    Math.cos((a[0] * Math.PI) / 180) * Math.cos((b[0] * Math.PI) / 180) * Math.sin(dLo / 2) ** 2;
  return 2 * R * Math.asin(Math.sqrt(x));
}

/** Calls grouped by incident id (multi-scene calls count toward each incident). */
export function groupCallsByIncident(calls: CallRecord[]): Map<string, CallRecord[]> {
  const map = new Map<string, CallRecord[]>();
  for (const c of calls) {
    const ids = c.incident_ids?.length ? c.incident_ids : c.incident_id ? [c.incident_id] : [];
    for (const id of ids) {
      if (!map.has(id)) map.set(id, []);
      map.get(id)!.push(c);
    }
  }
  return map;
}

/**
 * An incident's geography, oldest first: its geocoded call stops (the path —
 * same order as the call spine) or, failing that, its pin. Empty = not plotted.
 */
export function incidentPoints(inc: IncidentRecord, calls: CallRecord[] | undefined): LatLon[] {
  const stops = (calls ?? [])
    .filter((c) => c.location_coords)
    .slice()
    .sort((a, b) => a.started_at.localeCompare(b.started_at))
    .map((c) => [c.location_coords!.lat, c.location_coords!.lng] as LatLon);
  if (stops.length >= 2) return stops;
  if (inc.location_coords) return [[inc.location_coords.lat, inc.location_coords.lng]];
  return stops;
}

/** Worst-first, then most recent (UI_REDESIGN.md §5.1). */
export function worstFirst(incidents: IncidentRecord[]): IncidentRecord[] {
  return incidents
    .slice()
    .sort((a, b) => severityRank(b.severity) - severityRank(a.severity) || b.started_at.localeCompare(a.started_at));
}

export const NEAR_CAMERA_KM = 3.5;

export interface NearCamera { cam: Camera; km: number }

/**
 * Nearest cameras to an incident. For a path, distance is to ANY stop but
 * weighted toward the newest one, so a pursuit surfaces the cameras at its
 * head first (GEV "NEAREST", path-aware as in the mockup). `km` is the plain
 * distance to the nearest stop/pin; ranking uses the weighted score.
 */
export function nearestCameras(points: LatLon[], cameras: Camera[], k = 4, maxKm = NEAR_CAMERA_KM): NearCamera[] {
  if (!points.length) return [];
  const last = points.length - 1;
  return cameras
    .map((cam) => {
      let raw = Infinity;
      let score = Infinity;
      points.forEach((p, i) => {
        const d = km(p, [cam.lat, cam.lon]);
        raw = Math.min(raw, d);
        score = Math.min(score, d * (1 + (last - i) * 0.5));
      });
      return { cam, km: raw, score };
    })
    .filter((x) => x.score < maxKm)
    .sort((a, b) => a.score - b.score)
    .slice(0, k)
    .map(({ cam, km: d }) => ({ cam, km: d }));
}

/**
 * Coarse 2D viewshed cone (GEV idea #4). APPROXIMATE: built from the
 * published direction of travel, not a surveyed heading/FOV — label it so
 * wherever it is drawn. Cameras with no usable direction get no cone rather
 * than a made-up one.
 */
export function viewshedWedge(cam: Camera, rangeKm = 0.8, fovDeg = 50): LatLon[] | null {
  if (cam.heading_deg == null) return null;
  const pts: LatLon[] = [[cam.lat, cam.lon]];
  const cosLat = Math.cos((cam.lat * Math.PI) / 180);
  for (let a = -fovDeg / 2; a <= fovDeg / 2; a += 5) {
    const b = ((cam.heading_deg + a) * Math.PI) / 180;
    pts.push([cam.lat + (rangeKm / 111) * Math.cos(b), cam.lon + (rangeKm / (111 * cosLat)) * Math.sin(b)]);
  }
  return pts;
}

// ── Fused situational context ────────────────────────────────────────────────
export const CONTEXT_KM = { aircraft: 4, vessel: 3, road: 2 };

export interface IncidentContext {
  aircraft: { a: AircraftTrack; km: number }[];
  vessels: { v: VesselTrack; km: number }[];
  road: { e: Ny511Event; km: number }[];
}

function nearestKm(points: LatLon[], lat: number, lon: number): number {
  return points.reduce((m, p) => Math.min(m, km(p, [lat, lon])), Infinity);
}

export function contextFor(
  points: LatLon[],
  aircraft: AircraftTrack[],
  vessels: VesselTrack[],
  events: Ny511Event[],
): IncidentContext {
  const near = <T,>(items: T[], pos: (t: T) => LatLon | null, r: number) =>
    items
      .map((t) => {
        const p = pos(t);
        return { t, km: p ? nearestKm(points, p[0], p[1]) : Infinity };
      })
      .filter((x) => x.km <= r)
      .sort((a, b) => a.km - b.km);
  return {
    aircraft: near(aircraft, (a) => (a.lat != null && a.lon != null ? [a.lat, a.lon] : null), CONTEXT_KM.aircraft)
      .map(({ t, km: d }) => ({ a: t, km: d })),
    vessels: near(vessels, (v) => (v.lat != null && v.lon != null ? [v.lat, v.lon] : null), CONTEXT_KM.vessel)
      .map(({ t, km: d }) => ({ v: t, km: d })),
    road: near(events, (e) => [e.lat, e.lon], CONTEXT_KM.road).map(({ t, km: d }) => ({ e: t, km: d })),
  };
}

/** Bbox around a set of points, padded by `padKm`. */
export function bboxAround(points: LatLon[], padKm: number) {
  if (!points.length) return null;
  const lats = points.map((p) => p[0]);
  const lons = points.map((p) => p[1]);
  const dLat = padKm / 111;
  const midLat = (Math.min(...lats) + Math.max(...lats)) / 2;
  const dLon = padKm / (111 * Math.max(0.2, Math.cos((midLat * Math.PI) / 180)));
  return {
    south: Math.max(-90, Math.min(...lats) - dLat),
    north: Math.min(90, Math.max(...lats) + dLat),
    west: Math.max(-180, Math.min(...lons) - dLon),
    east: Math.min(180, Math.max(...lons) + dLon),
  };
}

// ── Deep links: #inc=<id>&cam=<cameraId>&tour ───────────────────────────────
export interface WallLink { inc: string | null; cam: string | null; tour: boolean }

export function parseWallHash(hash: string): WallLink {
  const p = new URLSearchParams(hash.replace(/^#/, ""));
  return { inc: p.get("inc") || null, cam: p.get("cam") || null, tour: p.has("tour") };
}

export function wallHash(link: WallLink): string {
  const parts: string[] = [];
  if (link.inc) parts.push(`inc=${encodeURIComponent(link.inc)}`);
  if (link.cam) parts.push(`cam=${encodeURIComponent(link.cam)}`);
  if (link.tour) parts.push("tour");
  return parts.length ? `#${parts.join("&")}` : "";
}

/** "On air": a live call is on one of the incident's talkgroups right now. */
export function onAirIncidentIds(incidents: IncidentRecord[], activeCalls: CallRecord[]): Set<string> {
  const live = new Set(activeCalls.map((c) => c.talkgroup_id).filter((t): t is number => t != null).map(String));
  return new Set(
    incidents.filter((i) => (i.talkgroup_ids ?? []).some((t) => live.has(String(t)))).map((i) => i.incident_id),
  );
}

// ── NEXRAD sample near an incident ───────────────────────────────────────────
// Reads the same IEM n0r composite tile the Weather Radar layer draws (IEM
// sends ACAO: *), and maps pixel colours back to the NWS reflectivity scale.
// Approximate by construction — label it so.
const N0R_PALETTE: [number, number, number, number][] = [
  [5, 4, 233, 231], [10, 1, 159, 244], [15, 3, 0, 244], [20, 2, 253, 2], [25, 1, 197, 1], [30, 0, 142, 0],
  [35, 253, 248, 2], [40, 229, 188, 0], [45, 253, 149, 0], [50, 253, 0, 0], [55, 212, 0, 0], [60, 188, 0, 0],
  [65, 248, 0, 253], [70, 152, 84, 198], [75, 253, 253, 253],
];
const RADAR_TILE = "https://mesonet.agron.iastate.edu/cache/tile.py/1.0.0/nexrad-n0r-900913";

function pixelDbz(r: number, g: number, b: number): number {
  let best = 0;
  let bestD = Infinity;
  for (const [dbz, pr, pg, pb] of N0R_PALETTE) {
    const d = (r - pr) ** 2 + (g - pg) ** 2 + (b - pb) ** 2;
    if (d < bestD) { bestD = d; best = dbz; }
  }
  return bestD < 60 * 60 ? best : 0;
}

/** Max reflectivity (dBZ) within ~radiusKm of a point, or null if it can't be read. */
export async function sampleRadarDbz(lat: number, lon: number, radiusKm = 5): Promise<number | null> {
  const z = 9;
  const n = 2 ** z;
  const xf = ((lon + 180) / 360) * n;
  const latR = (lat * Math.PI) / 180;
  const yf = ((1 - Math.log(Math.tan(latR) + 1 / Math.cos(latR)) / Math.PI) / 2) * n;
  const tx = Math.floor(xf);
  const ty = Math.floor(yf);
  const img = new Image();
  img.crossOrigin = "anonymous";
  img.src = `${RADAR_TILE}/${z}/${tx}/${ty}.png?_=${Math.floor(Date.now() / 300000)}`;
  try {
    await img.decode();
  } catch {
    return null;
  }
  const canvas = document.createElement("canvas");
  canvas.width = 256;
  canvas.height = 256;
  const ctx = canvas.getContext("2d");
  if (!ctx) return null;
  ctx.drawImage(img, 0, 0);
  const px = Math.floor((xf - tx) * 256);
  const py = Math.floor((yf - ty) * 256);
  const kmPerPx = (40075 * Math.cos(latR)) / (n * 256);
  const rad = Math.max(1, Math.round(radiusKm / kmPerPx));
  const x0 = Math.max(0, px - rad);
  const y0 = Math.max(0, py - rad);
  const w = Math.min(256, px + rad) - x0;
  const h = Math.min(256, py + rad) - y0;
  if (w <= 0 || h <= 0) return null;
  let data: Uint8ClampedArray;
  try {
    data = ctx.getImageData(x0, y0, w, h).data;
  } catch {
    return null;   // tainted canvas — CORS changed upstream
  }
  let max = 0;
  for (let i = 0; i < data.length; i += 4) {
    if (data[i + 3] < 32) continue;
    max = Math.max(max, pixelDbz(data[i], data[i + 1], data[i + 2]));
  }
  return max;
}